It is well known that reusable drawing surfaces which can be easily marked and erased are desirable in many applications. A basic and well known example of such a device is the common school room chalk board. The chalk board is a generally black surface made of graphite, slate or some other material which can be marked with chalk. When the user desires to change the markings on the board he/she need only wipe the surface with a cloth, sponge or other soft material to remove previously existing chalk particles. The surface can then be remarked as desired.
In recent years there have been advances in the drawing surface art. For instance, new plastic surfaces such as white boards have been developed which can be marked, erased and re-used in a manner similar to the more traditional chalk board. These new surfaces, however, require the use of special writing utensils such as markers whose inks can be temporarily marked onto the plastic surface and removed with a cloth or soft material whenever the user desires.
It will be appreciated by those skilled in the art that both of these types of drawing surfaces have many undesirable properties. For instance, the chalk board is marked by scratching chalk dust onto the surface of the graphite board. This process creates dust which is generally distributed both into the atmosphere and onto the user's hands during the drawing process. Further, the erasing process basically entails smearing the chalk dust over the surface to enable heavier, more concentrated chalk marks to be made over the smeared dust. Not only does this tend to soil the user, but it makes further markings less distinct as they are made against a background of similarly colored, smeared chalk dust rather than the black color of a clean chalk board. Although the problem of partial erasure can be corrected by wiping the chalk board with a wet cloth, the chalk board is not readily marked when wet. Thus, total cleaning of the surface results in substantial down times between uses. Thus, it can be seen that both the drawing and erasing phase of chalk board use generates substantial quantities of undesirable dust that can soil a user and degrade the board's performance characteristics.
The plastic drawing surfaces or white boards that have been developed in recent times improve on the concept of chalk boards and overcome some of their weaknesses by providing a writing utensil with a less dusty transfer element. These transfer elements must still, however, be erased by smearing or transferring the markings onto another material such as a cloth. Thus, the user of these surfaces is still presented with the necessity of providing disposable or washable eraser material and the possibility of being soiled when using these boards. Further, the user is presented with similar performance degradation problems as a result of background smearing which are present in chalk boards although in a lesser degree.